1. Cardiac haemodynamics were studied in 14 male patients with phaeochromocytoma, in comparison with 33 normal male subjects and 65 males with essential hypertension.
2. At the time of the investigation, seven patients with phaeochromocytoma were hypertensive and seven were normotensive. Cardiac output was within normal limits. Total peripheral resistance was elevated in the hypertensive patients. Heart rate was elevated both in the normotensive and in the hypertensive patients, but decreased after surgical treatment.
3. The relationships between blood volume and blood pressure and between blood volume and cardiac output were the same as those observed in the control groups.
4. During tilt, a predominant systolic orthostatic hypotension was observed and was associated with decreased stroke volume and impaired adaptation of total peripheral resistance during tilt, indicating inadequate arteriolar and venous reflexes.
5. The study suggested that, except for tachycardia, the haemodynamic pattern of patients with phaeochromocytoma and with essential hypertension was nearly the same.